1. Technical Field of the Invention
The present invention relates to processing systems as may be used in system on a chip integrated circuits and related methods.
2. Description of Related Art
As is known, integrated circuits are used in a wide variety of electronic equipment, including portable, or handheld, devices. Such handheld devices include personal digital assistants (PDA), CD players, MP3 players, DVD players, AM/FM radio, a pager, cellular telephones, computer memory extension (commonly referred to as a thumb drive), etc. Each of these handheld devices includes one or more integrated circuits to provide the functionality of the device. As an example, a handheld FM radio receiver may include multiple integrated circuits to support the reception and processing of broadcast radio signals in order to produce an audio output that is delivered to the user through speakers, headphones, or the like. Many such integrated circuits include a processing device that executes a program that includes a sequence of instructions that are stored in a memory device.
FIG. 1 presents a schematic block diagram representation of a prior art processing system 120. In particular, the processing system 120 is presented for executing a main program 112. Processing system 120 includes a processor 100 that is coupled to read only memory (ROM) device 102, random access memory (RAM) device 104, and flash memory device 106 via bus 108. As implemented in the prior art, a boot loader 110 is stored in ROM device 102. When the processing system 120 is booted, the boot loader 110 is executed by processor 100. Boot loader 110 includes operational instructions that cause the processor to retrieve the main program 112 and associated data stored in flash memory device 106 or on other external media, and to copy the main program 112 to the RAM device 104 (the copy being shown as main program 112′). The boot loader 110 further includes an instruction to jump to the main program 112′ stored in the RAM device 104 to begin execution of the main program 112′.
One problem with this prior art implementation is the amount of time required to execute the boot program. In particular, if the main program and associated data are lengthy, and/or if these files are encrypted and must be decrypted prior to copying and storage in RAM device 104, the copying and storage can require an undesirable amount of time. The need exists for a processing system that can be powered off and booted in an effective manner requiring as little time as possible, particularly for use in system on a chip integrated circuits and in handheld electronic devices.